(a) Technical Field
The present invention relates to system and method for indicating fuel efficiency of a flexible fuel vehicle which improve reliability of a fuel efficiency indication in a cluster and a calculation of an actual fuel efficiency by increasing accuracy of a actual fuel mix ration determination.
(b) Background Art
Since FFVs (Flexible Fuel Vehicle) use a mixture of gasoline and ethanol as the fuel, fuel efficiency varies depending on the contents of the fuel, thus causing an error in a fuel efficiency indication and a DTE (Distance To Empty) indication in a cluster. Since the fuel is different in fuel properties for each area, error occurs in indicating the actual vehicle fuel efficiency and cluster fuel efficiency. Specifically, as a vehicle travels, the engine control unit (ECU) may calculate the traveling fuel efficiency, but the content of the fuel may not be reflected, thus is may be difficult to indicate the accurate fuel efficiency value.
In particular, since there is a difference in content of water in the same fuel, depending on the areas, it may be necessary first to determine the mix ratio of fuel to more accurately calculate the fuel efficiency. In addition, since the information is output to a user via a cluster, it is important to reflect the information to the cluster indication information.
In the gasoline/diesel vehicles presently on the market, an engine control unit (ECU) transmits a FCO (fuel consumption signal) to a cluster through CAN communication based on the fuel efficiency calculated using the revolutions per minute (RPM) and the amount of intake air during traveling. In addition, the cluster calculates and indicates the cluster fuel efficiency based on the information. In other words, the cluster outputs an increased fuel efficiency at a reference value and reflects the fuel efficiency calculated during traveling.
In FFVs, there is a difference of 20% or more in fuel efficiency, depending on the content of ethanol fuel and it is difficult to reflect a difference in fuel efficiency according to the mix ratio of fuel generated when filling the fuel tank with fuel. Thus, it may be difficult to indicate an accurate fuel efficiency value and rely on the data. Furthermore, when fuel includes different mix ratios of fuel, it may be difficult to correct errors in the fuel efficiency output.
In one exemplary prior art, alcohol fuel in a fuel tank is injected from a secondary injection valve in a normal status, while gasoline in a fuel tank is injected from a primary injection valve in starting the engine, in a cold environment, or in a high intake stroke. Furthermore, when a difference between the actual air-fuel ratio and a target air-fuel ratio is above a set value in feedback control the air-fuel ratio of a gas mixture in a normal status, gasoline with high heat is injected at the amount of correction fuel in feedback control of the air-fuel ratio. Accordingly, the amount of correction fuel reduces compared to when alcohol fuel with low heat is used as correction fuel, thus, the amount of fuel sticking to the inner wall of an intake channel reduces and fuel is more quickly supplied to an operation chamber. Therefore, the following responsiveness in feedback control of air-fuel ratio is improved and the fuel efficiency may be improved.
However, even in the technology of the related art, the fuel efficiency is reflected after traveling for a predetermined time and not after the fuel has been filled, thus decreasing the initial reliability.
The description provided above as a related art of the present invention is just for helping understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.
In the related art, it was general to find out the mix ratio of the filled fuel and find out the fuel efficiency, by driving a vehicle for a predetermined time and leaning the result of the driving to find out the fuel efficiency.
However, according to such a method, since it was required to drive a vehicle for a predetermined time, it was difficult to guide accurate fuel efficiency, and accordingly, the fuel efficiency rapidly changes after a little time, so the consumers were confused and complained in some cases.